Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 181918

Area Forecast Discussion
National Weather Service Grand Rapids MI
318 PM EDT Fri May 18 2018

Synopsis/Short Term/Long Term/Marine/Hydro

Issued at 318 PM EDT Fri May 18 2018

Low pressure will move north from the Ohio Valley spreading rain
into Lower Michigan tonight and Saturday. The low will pull away
on Saturday night but another low will bring more showers late
Sunday into early next week. Fair weather should return by the
middle of the week.


.SHORT TERM...(This evening through Sunday night)
Issued at 318 PM EDT Fri May 18 2018

Timing the rain moving up from the south tonight is the primary
forecast challenge. Slowed down the arrival a bit from the
previous forecast based on current radar and short range model
trends. Otherwise, no major changes were made to the previous

Thunder chances tonight and Saturday are low given limited
instability. Rain should be ending from west to east on Saturday
night with surface ridging bringing fair weather and near normal
temperatures for Sunday.

.LONG TERM...(Monday through Friday)
Issued at 318 PM EDT Fri May 18 2018

Flow regime does not change much through next week with the
persistent upper troughing across eastern Canada holding in
place. We will continue to see occasional bouts of rain
interspersed with fair weather as sfc lows move along the wavy
front that has been across the Great Lakes/Ohio Valley for the
past few weeks.

After a weak sfc low moves through early in the week with some
showers we can expect a stretch of mostly fair weather Wednesday
into Friday as a sfc high builds south from Canada. The high moves
east with return flow by the end of the week along with an
increasing chance of showers.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 150 PM EDT Fri May 18 2018

VFR conditions will continue into this evening then slowly
deteriorate as showers move in from the south. IFR conditions will
move in after midnight and continue into Saturday morning. East
winds will gust to 20 knots at times.


Issued at 318 PM EDT Fri May 18 2018

Offshore winds will continue through Saturday and then go north
with waves expected to remain below 4 feet through Sunday.


Issued at 318 PM EDT Fri May 18 2018

River levels are high across southern Lower Michigan. The rivers in
central Lower Michigan are near to a little above normal. No river
flooding is ongoing. We are not expecting significant amounts of
rain, with less than an inch of rain expected through Monday for
most locations. This may lead to a slowdown or pause of the river
level falls.




LONG TERM...Ostuno
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